Inhibitors bases on fluoromethyl ketones. The mechanism of inhibitions of serine proteases (initially chymotrypsin) by peptidyl-fluoreomethyl ketones will be investigated. Questions of interest are: 1) Do all peptidyl-fluoromethyl ketones form adducts with the active site serine? 2) If they do, is the hydroxyl group of the resulting hemiacetal ionized? 3) What kind of interactions occur between amino-acid components of the inhibitor and the active site. These investigations will involve kinetic studies and x-ray crystallography of inhibitor enzyme complexes. This information will be used to develop strategies for the design of improved inhibitors for other serine proteases. Of primary interest is human leucocyte elastase. A new kind of active site directed inhibitor will be synthesized based on fluoromethyl ketones; targets: carboxypeptidase and angiotensin converting enzyme. Inhibitors of enzyme which utilize Schiff bases will also be synthesized, as well as inhibitors for acyl-transfer enzymes. A methionine salvage pathway. We shall continue our investigation of the pathway whereby 5'-S-methyl adenosine is converted to methionine. Intermediates and enzymes involved will be characterized. Lactyl-CoA dehydratase. An enzyme has been isolated from C1. propionicum which converts lactyl-CoA to acrylyl-CoA. The mechanism of this unusual reaction will be investigated, to determine whether a radical process is involved and what the role, if any, is of the cofactors (flavin, Fe/S centers). The composition and metabolic role of the multi-enzyme complex, of which the dehydratase is a part, will be examined.